Drive heat-exchanger unit

ABSTRACT

A transmission/heat exchanger unit includes a transmission having an input and at least one output and a heat exchanger, which is assigned to the output side of the transmission and is connected to said transmission at least indirectly via connecting lines. A duct or ducts route fuel, and is/are integrated in the case of the transmission, and extend(s) at least over part of the axial extent of the case to an end face of the transmission on the output side. A retaining device is provided for fastening the heat exchanger to the end face of the case of the transmission on the output side. The connecting lines that couple the fuel-routing duct or ducts in the transmission with the heat exchanger are integrated in the retaining device. Complementary connections of a standard type and size, which are located on the retaining device and the transmission case, are provided for fuel routing and for fastening the retaining device.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a 35 U.S.C. §§371 national phase conversionof PCT/EP2004/003354 filed 30 Mar. 2004, which claims priority of GermanApplication No. 103 14 733.0 filed 31 Mar. 2003. The PCT InternationalApplication was published in the German language.

The invention relates to a transmission/heat exchanger unit.

When transmissions, in particular automatic transmissions, are used indrive trains, it is known to assign to these transmissions a heatexchanger which is arranged on the output side. In this case, theconnection of the heat exchanger to the transmission takes place viahose lines and/or pipe lines. These must be adapted in terms of theirlayout to the requirements of the corresponding transmission and,furthermore, must be connected accordingly to the transmission and tothe heat exchanger respectively. In the event of an improper connectionor particular loads, leakage losses may occur, which result in a loss offuel and an environmental hazard. This means that the time intervals forfilling up with new fuel, that is with a medium which is necessary foroperating the transmission, for example in the form of lubricant and/orcontrol medium, are relatively short. A further substantial disadvantageof such a coupling between the heat exchanger and transmission is thatthe line routing must also be taken into account in the design of thetransmission in respect of the construction space required.

To solve these problems, DE 196 25 357 A1 discloses a version with ductsfor fuel and/or coolant which are integrated in the case wall of thetransmission and which extend onto the end face of the transmission. Theheat exchanger is arranged on this end face. A substantial disadvantageof the direct arrangement, in particular by flanging, of the heatexchanger at the end of the transmission is, on the one hand, that thecorresponding connections for fastening the heat exchanger and couplingthe ducts must always be adapted to the actual heat exchanger solution.Furthermore, these must be designed correspondingly or additionalmeasures must be taken in order always to ensure a leak tight connectionof the heat exchanger.

Assignments of heat exchangers to structural transmission units,furthermore, are already known from the following publications:

-   -   1. EP 0 812 746 A2    -   2. DE 196 25 357

A drive subassembly with a retarder and with a heat exchanger is alreadyknown from the publication EP 0 812 746 A2. In this case, the retarder,the heat exchanger, an adaptor and, if appropriate, a transmission aredirectly assembled together mechanically and are connected conductivelyto one another by means of the ducts of the adaptor. The retarder isflanged on the transmission. The adaptor performs a plurality offunctions simultaneously: on the one hand, it connects said componentsmechanically and, furthermore, it makes conducting connections betweenthese by means of its ducts. This solution allows a rapid and directconnection of the heat exchanger to the retarder, with hoses beingavoided completely. In this case, as a rule, the adaptor is arranged inthe rear region of the transmission and serves for coupling between theretarder and the heat exchanger. Via the heat exchanger, it is possible,furthermore, also to cool the media of other components. This, however,necessitates the correspondingly complicated line routing which,particularly with the retarder being interposed, either already has tobe taken into account as a preliminary or else is led around the latter.

A version of the heat exchanger integrated in a transmission is alreadyknown from DE 196 25 357 A1. The heat exchanger is arranged as anintegral part of the transmission case. Preferably, in this instance,the heat exchanger is integrated directly into the transmission case.This takes place in that ducts for the oil/water or air routing are castor worked directly into the transmission case. The same applies to thesupply of the medium to be cooled to the heat exchanger and theconnection pieces for the cooling medium. If the ducts are worked intothe case, in particular the case wall, they may be provided in such away that they are closed from the outside via a cover plate. It isconceivable, furthermore, for the heat exchanger to be designed as aflat disk-shaped unit which is mounted virtually positively onto atransmission side which is prepared correspondingly in the caseconfiguration. Especially in applications with retarders, this solutionaffords the advantage that, in this, there is no need to have to routethe cooling water lines from the engine past the transmission to therear, since the connection can already be provided at the front end ofthe transmission. A substantial disadvantage of this version, however,is that, particularly in the case of integrated ducts, there is noseparate heat exchanger provided, but, instead, the exchangepossibilities taking place via the intermediate walls between the ductsassume the function of the heat exchanger. In the version illustrated,the supply of coolant takes place at any desired point on thetransmission. With integration in the case wall, however, it isnecessary, to ensure an optimum cooling action, to providecorrespondingly long line paths which, in turn, are reflected in thecorresponding preparation of the case or else in the size of the heatexchanger. Moreover, the integration provided in the case leads to avery special design. The construction space required for this purpose isalways used up. As regards use in buses, however, the necessary freespaces for the construction spaces required for this purpose are notalways available in all directions.

SUMMARY OF THE INVENTION

The object on which the invention is based was, therefore, to provide atransmission/heat exchanger unit for use in drive trains, in such a waythat said disadvantages are avoided and, in particular, unnecessaryleakage losses are ruled out and a simple and reliable fuel routing viathe heat exchanger is ensured. Furthermore, the solution according tothe invention is to be distinguished by a low outlay in structural andmanufacturing terms. The number of components required needs to beminimized considerably and leak tightness and a low-stress coupling ofthe most diverse possible heat exchangers to the transmission are to beensured.

According to the invention, in the transmission/heat exchanger unit, theheat exchanger is arranged on the transmission, preferably directly onthe output side. The tie-up of the heat exchanger in this case takesplace via a retaining device. The retaining device is fastened to thetransmission, in particular the output-side end face of the case of thetransmission. According to the invention, the connecting lines betweenthe transmission and the heat exchanger, which function as a supply anddischarge line coming from the heat exchanger, are integrated at leastpartially into the wall of the retaining device, that is integrallyformed on the wall to form part of the wall. Preferably, they may alsobe arranged completely in the wall of the retaining device, that is tosay be surrounded completely by the retaining device. As a result, theconnecting lines functioning as a supply and discharge line to and fromthe heat exchanger become integral parts of the retaining device. Theline paths between the output from the transmission and the input to theheat exchanger can thereby be kept very short. Furthermore, the spaceused in the housing for the retaining device is utilized in an optimumway, so that no additional construction space has to be taken intoaccount in the design of the transmission/heat exchanger unit. Theconnections on the heat exchanger are not subjected to bending stress,as in the case of solutions directly flanged on.

By means of “intelligent” holders, variability for a multiplicity ofapplications can in this case be achieved, in particular because thechanges of heat exchangers, in comparison with holders, are verycomplicated and consequently entail high costs.

The mutually complementary connections on the transmission case and theretaining device for the fuel to be routed and/or the fastening arepreferably of standardized design. This makes it possible to provide acarrier element suitable with regard to this coupling for a multiplicityof the most diverse possible heat exchangers. The carrying element, inturn, preferably has likewise standardized connections for the heatexchanger.

The retaining device in this case assumes mainly the carrying andsupporting function for the heat exchanger and, furthermore, an adaptorfunction for the connection of different heat exchangers. Preferably,for this purpose, the mutually complementarily designed connections forfastening the heat exchanger are arranged on the output-side end face ofthe case. This arrangement preferably is in a case wall regionreinforced in a plane oriented transversely to the axis of rotation.This reinforcement in this instance extends over the entire axial extentof the transmission case or else at least over that part in which thefuel-routing ducts are arranged.

Furthermore, this arrangement or tie-up of the heat exchanger via theretaining device ensures that any desired heat exchangers can be coupledto the transmission, without their configuration also having to bedesigned in light of the bend-stressed mechanical and media-routingconnection to the case. This, then, can be shifted to the retainingdevice which may be designed as standard for specific sizes, dependingon the transmission design, in particular the case design. Standardizedor conventional heat exchangers may therefore be employed. Theindividual connections to the heat exchanger from the retaining deviceeither then are designed to fit correspondingly, that is to say tooverlap directly with the heat exchanger, or, when the heat exchanger isexchanged, may, if necessary, be implemented via short lines in theregion of the retaining device. Preferably, however, standardizedconnections in terms of type, dimensioning and arrangement on theindividual elements are also selected between the connecting lines inthe retaining device and the connections on the heat exchanger.

The connection for the coolant on the heat exchanger is provideddirectly on the retaining device. The media required for operating thetransmission are preferably routed in the transmission likewise in ductsintegrated in the case. This routing allows the direct transition to theretaining device of the heat exchanger. In this instance, theconnections provided for this purpose on the case and of the retainingdevice are to be arranged in a correspondingly complementary manner, inorder to ensure a reliable overlap. The retaining device is in thisinstance preferably braced in the axial direction with respect to thecase via a seal and/or is sealed off and axially braced via insertiontubes in each case by means of at least two radially sealing O-rings orthe like.

The tie-up of the connections for the coolant to the retaining deviceaffords the advantage that, in the event of a change of the connections,the fastening of the heat exchanger to the holder does not have to beopened or modified.

The fuel-routing ducts in the case wall in this instance extend over atleast part of the axial extent of the case through the case wall in thedirection of the output side with regard to the transmission of powerfrom the input of the transmission to the output.

The heat exchanger may be designed as a separate component or else becombined with the transmission cover to form a functional unit, in thatthe retaining device is fastened, for example, via the transmissioncover to the case. In this instance, however, the transmission cover isalso equipped with the corresponding ducts for the routing of operatingmedium.

BRIEF DESCRIPTION OF THE DRAWING

The solution according to the invention is explained below by means ofFIG. 1 which is a diagrammatic simplified illustration in perspectiveview of the basic setup of a transmission/heat exchanger unit configuredaccording to the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

A heat exchanger unit 1 comprises a transmission 2 with an input Ecouplable to an engine and with at least one output A. A heat exchanger3 is assigned to the transmission 2 on the output side, that is to-sayat the output A, and it can be coupled at least indirectly to thefuel-routing lines and/or ducts 4 of the transmission. The heatexchanger 3 is in this instance mounted on the transmission 2, inparticular on its case 6, via a retaining device 5. According to theinvention, the connecting lines 7 and 8 between the heat exchanger 3 andthe transmission 2 are integrated in the retaining device 5. In thisinstance, at least in each case two connecting lines, in the instanceillustrated the connecting line 7 and the connecting line 8, areprovided. Depending on the functional assignment, one of the twoconnecting lines functions as an inflow line to the heat exchanger 3,while the other functions as the outflow line. In the instanceillustrated, for example, the connecting line 7 functions as an inflowline and the connecting line 8 as an outflow line. The two connectinglines are connected to corresponding lines or ducts 4 in thetransmission 2. These are preferably lines or ducts which are integratedin the wall 9 of the case 6 and they serve for the routing of mediarequired for operating the structural transmission unit. These are, as arule, the transmission oil which is used for the purpose of lubricationor else for the purpose of the activation of shift elements. The oil isalso used for the purpose of cooling and for hydrodynamics, that is tosay the transmission of power in the converter. It is conceivable,furthermore, for the oil to supply hydrodynamic components. Here, too,at least two lines 4.1 and 4.2 are provided, one being couplable to theconnecting line 7 arranged in the retaining device 5 and functioning asan inflow line, while the other can be connected to the connecting line8 arranged in the retaining device 5, so as to form a circuit 10.Coupling takes place via corresponding connections 11 and 12 on the case6. Two fuel-routing lines or ducts 4.1 and 4.2 or connecting lines 7 and8 are illustrated, but it is also conceivable to use a plurality of suchducts and lines which, however, must be equipped appropriatelycomplementarily to one another or with corresponding connections on thecase 6 of the transmission 2 and the retaining device 5. In thisinstance, the connections 11 and 12 on the output-side end face 13 ofthe transmission 2 can then be connected to connections 14 and 15 on theend face 16 facing the transmission 2. This type of connection may beimplemented in many different ways. It is critical merely that theconnections 11 and 12 and also 14 and 15 are designed complementarily toone another, so that, in actual fact, a circuit 10 which may be designedas an open or closed circuit is produced. The coupling implementedbetween the individual connections 11 and 14 or 12 and 15 may bedesigned in many different ways. This may take place positively and/ornonpositively. Preferably, however, the retaining device 5 is braced inthe axial direction with respect to the case 6, using interposed seals17. Insertion tubes with corresponding seals are often also used aloneor even in conjunction with the flat seals described. The retainingdevice is mounted on the case via the fastening on the case, whichfastening may take place nonpositively and/or positively.

Furthermore, the heat exchanger 3 is assigned a cooling circuit, notillustrated in detail here, which serves for the routing of coolingmedium. What can be seen in this regard are the connections 18 and 19for the coolant-routing ducts or lines which function as an inflow andan outflow line and which may be an integral part of an open or closedcircuit. By means of this solution according to the invention,complicated hose lines or pipe lines for connecting the heat exchanger 3to the transmission 2 are dispensed with. The connecting lines 7 and 8integrated into the retaining device 5 are in this instance preferablyintegrated at least partially into the wall 20, but preferablycompletely into the latter. In the instance illustrated, in each caseonly two connecting lines 7 and 8 are provided. It is also conceivable,however, according to the prevailing circumstances, to have a designwith a plurality of connecting lines, these then separately formingfuel-routing circuits. This also applies similarly to thecoolant-routing ducts.

The arrangement of the retaining device 5 on the case 6, in particularthe fastening of said retaining device, is in this instance carried outin such a way that the case cover 21 provided for closing off the casein the axial direction is not included. It is also conceivable, however,for example, to design the case cover 21 as an integral part of theretaining device.

Functioning is similar to the known arrangements of transmissions 2 withheat exchangers 3. The direct coupling and integrated lines in theretaining device 5 provide a highly compact transmission/heat exchangerunit 1 which is free of hose lines and/or pipe lines routed next to thisunit. The number of individual parts is minimized considerably, sincehere, in particular, there is only the retaining device with integratedducts or lines. The connections on the retaining device, in particularon the end face 16, are in this instance arranged in such a way thatthey are complementary to the arrangement of the connections 11 and 12on the case 6. To produce standardized heat exchangers 3, theconnections 14 and 15 are arranged at a distance from one anothertransversely to the theoretical prolongation of the axis of rotation atthe output A, this distance likewise being provided on the case 6. Theheat exchanger itself may be designed in any desired way. Preferably, itis designed, for example, in the plate type of construction. Otherversions may be envisaged.

1. A transmission/heat exchanger unit, comprising: a transmission havinga case, an input shaft couplable to an engine, at least one output on anoutput side of the transmission, and an output side end face of thetransmission on the output side of the transmission; a heat exchanger onthe output side of the transmission, connecting lines connecting theheat exchanger at least indirectly to the transmission; at least oneoil-routing duct integrated in the case of the transmission, eachoil-routing duct extending at least over part of the axial extent of thecase to the output side end face of the transmission; a retaining devicefastening the heat exchanger to the output-side end face of the case ofthe transmission; the connecting lines configured and operable to coupleat least one oil-routing duct in the transmission case with the heatexchanger, the connecting lines being integrated in the retainingdevice; and complementary connections, standardized in type anddimension, on the retaining device and the transmission case for routingof oil and for fastening the retaining device.
 2. The transmission/heatexchanger unit as claimed in claim 1, wherein the connecting lines arearranged at least partially in a wall of the retaining device.
 3. Thetransmission/heat exchanger unit as claimed in claim 1, furthercomprising at least a first connection and a second connection providedfor connecting coolant-routing lines to the heat exchanger.
 4. Thetransmission/heat exchanger unit as claimed in claim 3, wherein thefirst and second connections for coolant are arranged on the retainingdevice and wherein one of the first and second connections is coupled toa coolant supply line, and the other of the first and second connectionsis coupled to a coolant discharge line.
 5. The transmission/heatexchanger unit as claimed in claim 3, wherein at least one of the firstand the second connections are arranged directly on the heat exchanger.6. The transmission/heat exchanger unit as claimed in claim 1, whereinthe heat exchanger is designed as a separate unit.
 7. Thetransmission/heat exchanger unit as claimed in claim 1, wherein theoil-routing ducts are cast or worked in a wall of the case.
 8. Thetransmission/heat exchanger unit as claimed in claim 7, wherein theoil-routing ducts are cast or worked in a reinforcement of the wall ofthe case.
 9. The transmission/heat exchanger unit as claimed in claim 1,wherein the retaining device is fastened to the output-side end wall ofthe case in a region of an axial reinforcement of the end wall, whereinthe connection is free of a fastening to a transmission cover closingthe case on the output side.
 10. The transmission/heat exchanger unit asclaimed in claim 1, wherein connections of standardized design in termsof type and dimensioning are provided on the retaining device forcoupling to complementary connections on the heat exchanger.
 11. Thetransmission/heat exchanger unit as claimed in claim 1, furthercomprising a transmission cover, wherein the retaining device forms anintegral unit with the transmission cover.
 12. The transmission/heatexchanger unit as claimed in claim 11, wherein the retaining deviceextends through the case cover and has the connections for coupling tothe connecting lines provided in the carrying element.
 13. Thetransmission/heat exchanger unit as claimed in claim 1, wherein theoil-routing ducts are arranged in the case wall on both sides of atheoretical prolongation of the axis describing the output, wherein thesupply lines are arranged on one side of the axis, and the dischargelines are arranged on the other side of the axis.